R and M Transmission Poor transmission rebuild and no warranty Marne Michigan

Brought trans to shop about a year and 1/2 ago to have rebuilt after it overheated.  Shop freshened up the trans(new clutches/steels) and replaced some hard parts that were worn out, installed shift kit(was told), hardened sun shell(maybe it looks like a stock piece to me), new rear planetary(more on that below) and included new rebuilt torque converter and trans cooler.  Took trans home, flushed lines and radiator cooler with 2 cans of Kooler Kleen and then 2 quarts of new ATF with compressed air in between, very very clean no obstructions.  Also added new cooler and installed temp gauge.  Followed start up instructions to a "T", checked for leaks(none)and filled to proper level.  I don't drive the vehicle often, only when needed (truck).  Shifted fine everything seemed good.  Fast forward to last month noticed gear whine in first gear that stopped when shifting to 2nd.  Was going to contact shop on vacation and ask about it.  Soon after was taking off from stop normally and "BANG" trans exploded internally and no forward gears.  Towed home and dropped pan and LOTS of metal in the pan-looked like bearing pieces to me.  Fluid was gray from all the metal but smells brand new. Keep in mind this trans has less than 800 miles since the rebuild! Only tows light fishing boat occasionally and trans gauge never got past 150F since rebuild. Called shop told owner what happened and he made it sound like I did all sorts of things wrong installing it (like not bypassing the radiator cooler-I just couldn't justify doing that and from what I've read it's not the smart thing to do) and that I must not have flushed the lines good enough, etc.  So now I'm hesitant to take it back, he made it sound like it's all my fault that it failed.  So I pull it out again(what a pita on my back in the garage) and decided to take it apart myself to see what went wrong.  I found a missing bolt in the valve body, the 2/4 servo  shaft looks like it's been welded on??(never heard of or seen that before, talked to other trans shops and they thought it was a very poor mod to say the least)  but everything else looks ok aside from all the metal shavings until I get to the rear planetary (one of the hard parts that was supposedly replaced) . The bearing came apart and that is what started the catastrophic failure.  The bearing pieces and splines took out the(new) planetary, ring gear that it rides in, the sun gear, and possibly  the output shaft. So now I have to figure out what to do, I only got about 700 miles out of the trans, and I sure don't want to take it back after the negative conversation I had with owner.  I have been informed by a very knowledgeable trans builder that R & M probably put a Torrington bearing in the transmission BACKWARDS.  He has seen this in quite a few rebuilds and the trans always fails soon after the rebuild and always the rear planetary.  I think I’m going to try to fix it myself, can’t be any worse than my experience with RM, if I get more than 700 miles I guess I did pretty good being a rookie.  I have to just chalk it up to another hard lesson learned and just wanted to let others know about my experience-to say I’m bummed out about this is an understatement.    I can’t say my experiences with them have all been bad, in the past the owner has been good to me (fluid and filter change).   But that’s no concession now that I'm right back where I was before the rebuild, actually in worse shape now with all the internal damage.  Wouldn’t recommend this place after this experience and wish I would have done my homework before choosing them-if you are looking for a trans place I recommend reading Transmission Rebuild 101: Words From A Shop Manager's Perspective.  It opened my eyes quite a bit.